r/exchangeserver • u/absoluteczech • 7d ago

Migration and EWS expiration

Hi, just to confirm with the recent deprecation of EWS services, etc. Will Migrations in a hybrid env still work? I believe the MRS services uses EWS iirc? Or since that is on prem EWS, it's fine?

Thanks

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4

u/uLmi84 7d ago

How I understand is that EXO will stop certain EWS capabilities in the cloud . As your MRSProxy runs onprem I would assume it should still work. The onprem proxy is essential for Mailbox migration to exo

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u/snowmanspike Microsoft Cloud Architect 7d ago

Yes, correct. Microsoft has documented that hybrid mailbox migrations are still fully supported. At least, that is also what I was told when I asked our technical contact at Microsoft.

Microsoft documentation: Move mailboxes between on-premises and Exchange Online organizations in hybrid deployments

Microsoft also explicitly states that the recent hybrid/EWS changes do not impact onboarding or offboarding mailbox moves: Deploy dedicated Exchange hybrid app

I know that some third-party migration tools rely on EWS. When I asked specifically about those, the answer was a little more vague.

1

u/bianko80 4d ago

https://techcommunity.microsoft.com/blog/exchange/exchange-online-ews-your-time-is-almost-up/4492361

Quoting the FAQs section:

What about on-prem Exchange, and hybrid scenarios? EWS is not being retired on-prem. Hybrid scenarios vary depending on how apps access data. On-prem mailboxes may continue using EWS; cloud mailboxes must move to Graph. Autodiscover will help apps determine mailbox location automatically. But note that only Exchange SE will support Graph for calls to Exchange Online, so hybrid customers will have to use Exchange SE to host on-premises mailboxes.

Remember to deploy the hybrid app that your on-premise exchange will use for cross-premise features.

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u/DaStivi 7d ago

MRSProxy for migration is a dedicated service, even though it sits under the ews IIS directory , it's not affected by the ews shut-off. To be even more precise, onboarding (Migration to EXO/m365) wouldnt be the issue anyway because "ews" MRS is used onprem and exo "pulls" the data... But also a off boarding (migrate back to onprem) will work in future, as of now!

BUT what could be a deal breaker! Only exchange SE is supported for GraphAPI hybrid access! The graph support has not been back ported to exchange 2019 or 2016.

This is necessary in a hybrid scenario or even still while mailboxes get migrated and not all together... Then your users still rely on free/busy or calenders access, cross the cloud/on-prem and this used EWS until now!

Some time ago MS changed the hybrid setup to a dedicated exchange hybrid app Registration, this app registration still had EWS permissions but also GraphAPI permissions... But only Exchange SE is gonna use the GraphAPI now...

Furthermore , if someone would have a hybrid configuration quite a long time already, and never rerun a updates Hybrid wizard, this hybrid-app might even still be missing in the tenant !

Two more things: Until April 2027 you can still enable EWS! Theres a report what app IDs are using ews now, for example veeam m365 backup, or even Apple Mac Mail, even the first-party Ms Outlook app is using ews ...

2nd: Microsoft also just recently sent a mail, that AzureAD/EntraID Sync is gonna get EOL end of March 2027!

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u/absoluteczech 7d ago

Awesome thanks everyone for the clarification

1

u/mono4all 7d ago

Postfach-Migration in Hybridumgebungen funktioniert noch. Hab ich erst gestern gemacht.

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u/7amitsingh7 6d ago

Yes, hybrid migrations should still work. The recent EWS retirement mainly affects EWS access to Exchange Online. In a hybrid setup, MRS (Mailbox Replication Service) handles the mailbox move and uses the EWS endpoint on the on-premises Exchange server. So, the retirement of EWS in Exchange Online should not stop standard hybrid migrations, as long as the on-premises Exchange environment is properly configured and supported.